The Vickers microhardness of this alloy was unusually dependent on the heat treatment from 300 to 634K, inferring important microstructural changes and the presence of amorphous grains before its phase transition. Once the alloy is crystallized, the microhardness is characteristic of a brittle alloy, the main problem of these alloys. Within the amorphous state, other properties like freevolume, magnetic states and FeFe distances were followed by PALS and MS, respectively, to analyze those microstructural changes, thermally induced, which are of paramount interest to understand their brittleness problem.